Magnetically responsive switching apparatus

ABSTRACT

Magnetically responsive switches are provided which have contacts which are normally open or normally closed or sets of contacts which are respectively closed and open. In those switches having both the open and closed sets of contacts, provision is made for distinguishing between the presence of one controlling magnet or more than one. In the presence of one magnet, the set of contacts which is normally open is closed. The introduction of a second magnet will cause one or the other of the sets to open. Provision is made for adjustment of the responses to magnetic forces and to avoid the effects of residual magnetism.

United States Patent Primary Examiner-Bernard A. Gilheany AssistantExaminerR. N. Envall, .I r. Attorney-Posnack, Roberts & Cohen ABSTRACT:Magnetically responsive switches are provided which have contacts whichare normally open or normally closed or sets of contacts which arerespectively closed and open. In those switches having both the open andclosed sets of contacts, provision is made for distinguishing betweenthe presence of one controlling magnet or more than one. In the presenceof one magnet, the set of contacts which is normally open is closed. Theintroduction of a second magnet will cause one or the other of the setsto open. Provision is made for adjustment of the responses to magneticforces and to avoid the effects of residual magnetism.

PATENTED 15197! 3.621.417

SHEET 1 0r 2 INVI'IN'IUH. JOSEF HALABY MW M MAGNETICALLY RESPONSIVESWITCHING APPARATUS BACKGROUND Field Of Invention This invention relatesto magnetically responsive switches and more particularly to switchesfor use in burglar alarm systems.

In certain types of burglar alarm systems, a switch will be placed, forexample, on or adjacent a window to be operated by unauthorized openingof the window. One known technique for accomplishing this is by the useof a magnet and a magnetically responsive switch. The switch, in thiscase, can be located adjacent the window and the magnet on the windowsuch that movement of the latter will move the magnet and operate theswitch thereby initiating an alarm.

One deficiency of this known arrangement is that it has been foundpossible to employ an auxiliary magnet which is held stationary adjacentthe position of the first magnet while the first magnet is displaced. Asa consequence of this practice, it becomes possible to open the windowand displace the first magnet while preventing the switch fromoperating. This allows the opening the window without sounding thealarm.

It is an object of the invention to provide an improved magneticallyresponsive switch which avoids the aforedescribed problem.

Another object of the invention is to provide improved magnetic switcheswhich are nondirectionally oriented.

Still another object is to provide improved switches which are readilymanufactured by mass production techniques.

Magnetically responsive devices such as reed relays are known. Onedeficiency of the known devices is that residual magnetic effects caninterfere with the proper operation thereof.

Accordingly, it is a further object of the invention to provide improvedswitches which avoid the consequences of residual magnetic forces.

SUMMARY OF INVENTION In accordance with the invention, magneticallyresponsive switching apparatus is provided comprising two terminalsbetween which is located a magnetically responsive switching meansresponsive to the presence of a first magnet to maintain an open or aclosed circuit condition between the terminals and responsive to thepresence of said first magnet and a second magnet to change the circuitcondition between the terminals.

The above-noted switching means comprises in accordance with theinvention first and second contact means which are respectively open andclosed in normal condition. One of the contact means is responsive to afirst magnetic force which force is ineffective to change the open andclosed condition of the other contact means to assume the same open orclosed condition as said other contact means. The introduction of asecond magnetic force is effective to change the open or closedcondition of one of these contact means.

In further accordance with the invention, each contact means includesrelatively displaceable contacts. One of the contacts may be relativelyand the other displaceable, or both of the contacts may be displaceable.At least one of the contacts is of a nonmagnetic material to avoid theconsequences of residual magnetism. The aforesaid contact means eachinclude magnetically responsive spring means for displacing at least oneof the associated contacts, the spring means being normally positionedfor keeping the contacts of one of the contact means open and thecontacts of the second contact means closed.

As a feature of the invention adjustment means are provided to adjustthe responsiveness of at least one of the spring means to magneticforces the spring means preferably including a spring element with amagnetically responsive element attached thereto. According to a furtherfeature of the invention an envelope is provided encapsulating theaforesaid contact means.

In accordance with one embodiment of the invention the contacts of eachsection of the switch are inclusive of fixed contacts which areinterconnected in a continuous conductive structure.

According to a specific construction within the scope of the invention,one of the contacts is in the form of a ring encircling the othercontact which is mounted sn a spring element for radial displacementagainst the ring. According to another specific construction, the springmeans are cantilevered spring elements, one of which is normallyinclined against a fixed contact structure and the other of which isinclined away from the fixed contact structure.

Still another specific construction involves the use of two displaceablecontacts between which is mounted a magnetically responsive springelement capable of displacing either one or both of the associatedcontacts.

The above and further constructional features of the invention will befound in the detailed description which follows hereinafter.

BRIEF DESCRIPTION OF DRAWING FIG. 1 diagrammatically illustrates a firstembodiment of the invention including one switch section;

FIG. 2 diagrammatically illustrates a second embodiment of the inventionalso including one switch section;

FIG. 3. illustrates a variation of the construction of FIG. I withprovisions for adjustment:

FIG. 4 diagrammatically illustrates a variation of FIG. 2 for theincorporation of adjustment means;

FIG. 5 illustrates a two-section switching apparatus embodying theprinciples of FIGS. 1 and 2;

FIG. 6 illustrates a variation of the construction of FIG. 5 embodyingan adjustment means; and

FIG. 7 illustrates diagrammatically and in perspective a furtherembodiment of the invention.

DETAILED DESCRIPTION The switching apparatus of FIG. I comprises anenvelope I0 of glass into which extend two leads I2 and 14 constitutingrespective terminals of the switching apparatus. Attached to the lead 12is a fixed support 16 on which is supported an electrically conductivering 18 of copper or some other nonmagnetizable material. Support 16 isalso conductive so that a series circuit exists consisting of lead I2,support 16 and ring I8.

' Attached to lead 14 is a spring wire 20 which is of electricallyconductive material which is also preferably nonmagnetic.

A contact 22 of electrically conductive material is mounted on the freeend of spring wire 20 and a collar 24 of magnetically responsivematerial is mounted on wire 20.

The contact 22, being mounted sn spring wire 20. is free to undergoradial displacement so that it makes contact with ring 18. Since contact22, wire 20 and lead I4 are all electrically conductive, a seriescircuit can be completed between leads l2 and 14 by bringing contact 22into engagement with ring 18. It will be noted that the construction isnondirectional or that, in other words, magnetic force acting on element24 in any direction can bring contact 22 into engagement with ring 18provided that the magnetic force is sufficiently strong. It is also tobe noted that since ring 18 and preferably also contact 22 are of amaterial which is nonmagnetizable, there can be no residual magneticforce and consequently engagement between elements 18 and 22 cannot bemaintained once the applied magnetic force has been removed.

The switching apparatus illustrated in FIG. 2 also comprises an envelopeindicated at 26 into which enter leads 28 and 30 to which are attachedspring supports 32 and 34 of electrically conductive material. Contacts36 and 38 are mounted at the free ends of members 32 and 34 whichcontacts in engagement with one another.

normally hold these Members 32 and 34 include segments 40 and 42 ofsubstantially hemispherical shape. These segments enclose or encircle aspherical element 44 mounted on a spring member 46 supported at 48within the envelope 26. A collar 50 of magnetically responsive materialis mounted on the spring element 46 and is the means by which a magneticforce applied to the illustrated switching apparatus is effective tochange the open or closed condition of the contacts.

More particularly, a magnetic force applied to the switching apparatuswill act upon element 44 thereby to laterally displace the wire 46 whichin turn will carry with it the spherical member 44 which will operateagainst one or both of segments 40 or 42 as a consequence of which thecontacts 36 and 38 will separate.

As in the prior embodiment of the invention, contacts 36 and 38 and/orspherical member 44 are preferably of nonmagnetic material to avoid theeffects of residual magnetism. It is also to be noted that the switchingapparatus illustrated in FIG. 2 is nondirectional; as a consequencethereof, magnetic force in any direction will operate to open thecontacts which are otherwise normally closed The wire elements in FIGS.1 and 2 may be of spring steel wire such as piano or violin wire orother music wire. These elements may be fabricated in the form of a coilto increase their sensitivity.

In the embodiment of the invention illustrated in FIG. 3, a ring 52encircles a contact 54 mounted on a spring wire 56 encircled by amagnetizable collar 58. The wire 56 is mounted on a threaded member 58'accommodated within a threaded bore in an element 60 supported byretainers 62 and 64 on the interior of the envelope 66. An opening 68 isprovided at one end of the envelope to permit the insertion of anadjusting tool into a slot 70 at one end of element 58. The wire 56 isencircled by a loop 72 supported on the interior of the envelope 66 by asupport 74.

In this embodiment of the invention, adjustment of element 58 adjuststhe distance of the cantilever length of the structure with respect towhich the magnetic force is effective, Since contact 54 will bedisplaced longitudinally with wire 56, the ring 52 is given additionalheight to accommodate the same.

The embodiment of the invention illustrated in FIG. 4 illustrates thatthe spherical sections of FIG. 3 are given a cylindrical form asindicated at 80 and 82, the purpose of this being to accommodatelongitudinal adjustment of the supporting wire 84 on which sphericalmember 86 is mounted. Contacts 88 and 90 are in this embodiment of theinvention normally closed as previously explained with respect to theembodiment of FIG. 2.

All of the above-described embodiments of the invention are devices withsingle switching sections and share in common that they are generallynondirectional and preferably fabricated of materials which avoid theconsequences of residual magnetism. The embodiment of FIG. 5, however,combines the features of two such switches and comprises a normallyclosed and a normally open section connected in series and intended toachieve the object of distinguishing between the presence of a singleexternal magnet and more than one external magnet.

More particularly, the embodiment of FIG. includes a switch 100 in whichenter leads 102 and 104. Lead 102 has connected thereto a spring wire106 having thereon a collar 108 of magnetically responsive material, acontact 100 being mounted on the free end of wire 106. Contact 110 isencircled by ring 112 of electrically conductive, nonmagnetic materialwhich is held in fixed position by a support 114 mounted at end 116within the envelope 100. To the end 116 is mounted a displaceable springwire 188 supporting a spherical section 120 thereon upon which issuperposed a contact 122.

Contact 122 is normally in engagement with a contact 124 atop sphericalsection 126 supported on spring wire 128. Encircled by the sphericalsections 120 and 126 is a spherical member 130 mounted on a spring wire132 encircled by a collar 134 of magnetically responsive material.

The aforedescribed switching apparatus is composed of a series circuithaving two sets of contacts therein. one of these sets of contacts beingnormally open and the other set of contacts being normally closed. Thecircuit passes from lead 104 through spring wire 128, segment 126,contact 124, and contact 122 and thence via segment to spring wire 118.From this point the circuit continues through support 114, ring 112,contact 110 when in engagement with ring 112 and thence through springwire 106 to lead 102.

The strength of spring wire 106 is related to that of spring wire 132 toachieve the aforenoted function of distinguishing between the presenceof one external magnet or more than one external magnet. Moreparticularly, this relationship is as follows: if one magnet is broughtto the vicinity of envelope 100, collar 108 is activated and contact 110is brought against ring 112 and since the contacts 122 and 124 arenonnally closed, a circuit is completed between leads 102 and 104. Thisis effective in a conventional burglar alarm system to prevent an alarmfrom being sounded. It will be noted that the strength of spring 132will be sufficient for preventing collar 134 from being attracted by themagnet thus preventing sphere from being brought into engagement witheither of segments 120 or 126 whereupon there is no operating forcebrought into play on contacts 122 and 124. Assuming now that a secondmagnet is brought adjacent the envelope 100, the magnetic force of thissecond magnet will either be cumulative with the force of the firstmagnet or will be in opposition thereto. If the force is cumulative, thecombined magnetic forces will now be sufficient to attract collar 134 byovercoming the resistance of spring 132 and so displace collar 134whereupon one of the segments 120 or 126 will be engaged and contacts122 and 124 separated. On the other hand, if the second magnetic forceis in opposition to the first magnetic force, this will decrease themagnetic force acting on member 108 and contact 110 will be releasedfrom engagement with ring 112 and once again the circuit between leads102 and 104 will be opened.

The cumulative effect of the aforegoing is that a switching apparatus isprovided which responds to the presence of a first magnet by providing aclosed circuit, whereas the introduction of a second magnet will causethe circuit between leads 102 and 104 to be opened.

In the case of a burglar alarm system, the aforesaid switching apparatusis very useful. The presence of a first magnet, as is conventional,located for example on a window adjacent which envelope 100 is mounted,will cause the switching apparatus to constitute a closed circuit.Opening of the window by itself will remove the magnet, disengagecontact 100 from ring 122 thereby opening the circuit and causing analarm to ring. Should an attempt be made to gain unauthorized access bybringing a second magnet into juxtaposition with envelope 100 while thewindow is being opened, the presence of the second magnet will cause thecircuit to be opened as aforesaid and an alarm will be initiated therebyindicating this attempt to make an unauthorized entry.

The embodiment in FIG. 6 is similar to that of FIG. 5 in that itincludes two serially related sections, wherein there is employed anenvelope in which a ring 142 is supported in fixed position on a support144. A contact 146 is mounted on a spring wire 148 encircled by amagnetic collar 150, there being provision for adjustment by the use ofelements 152 and 154. Access to adjustment element 152 is providedthrough opening 156.

Cylindrical elements 158 and 160 support normally engaged contacts 162and 164 and are in turn supported on spring wires 166 and 168. Adisplaceable element 170 is supported on a spring wire I72 encircled bymagnetic element 174 and adjustment possibilities are provided by theuse of adjustment elements 176 and 178. Connections are made throughterminals 180 and 182.

As in the previous embodiment of the invention, contacts 162 and 165 arenormally closed, but contacts 142 and 146 are normally open. Contacts142 and 146, however, respond to the presence of a single magnet byclosing thereby providing a closed circuit between terminals 180 and182. The in troduction of a second magnet, however, will work on one ofthe sets of contacts as aforesaid to open the same, whereby an opencircuit will result between the terminals of this switching apparatus.

The embodiment illustrated in FIG. 7 includes an envelope 200 having 200terminals 202 and 204 to which are affixed cantilever springs 206 and208 of phosphor bronze or the like. Springs 206 and 208 respectivelysupport magnetic elements 210 and 212.'A fixed lead 214 is mountedwithin the envelope 200 and supports a fixed Z-shape contact structure216 of electrically conductive material. The end portions 218 and 220 ofstructure 216 effectively constitute contacts as do the end portions 222and 224 of springs 206 and 208. A magnetizable element 226 is supportedon envelope 200 to provide a magnetic screen to concentrate in thedirection of arrow 228 the applied magnetic field which can originatefrom a different direction depending on the relative position of theexternal influencing magnet.

Normally, spring 206 is yieldingly urged in the direction of arrow 229to a position of rest against contact 218 thereby providing a set ofnormally closed contacts Normally, contact 224 is spaced from contact220 to provide a set of normally open contacts.

The presence of a single external magnet, for example, on the outside ofelement 226 will operate one magnetic element 212 to displace spring 208and bring contact 224 into engagement with contact 220 as a consequenceof which a closed circuit will be caused to exist between terminals 202and 204. If then a second magnet is brought into a position of influencerelative to envelope 200, its force will either add to or oppose that ofthe first external magnet. If the combined magnetic forces arecumulative, they will operate on element 210 to displace spring 206 andpull contact 222 away from contact 218. If the forces are subtractive,there will no longer be sufficient force acting on magnetic element 212and the strength of spring 208 will pull contact 224 away from thecontact 220. As a consequence of this a switching apparatus is againprovided for distinguishing between the presence of one magnet on theone hand or more than one magnet on the other hand In the embodiment ofFIG. 7, adjustment possibilities are provided in the form of adjustmentscrews 230 and 232 engaging threaded bores in elements 234 and 236.

From the above it will be seen that the single section switching devicesof the invention are characterized by being nondirectional and free fromthe effects of residual magnetism. It will be seen that the multiplesection switching devices of the invention provide for thedistinguishing between different magnetic environments. In the multiplesection switching devices there are provided two sets of contacts, oneof which is normally open and the other of which is normally closed. Theopen set is brought to closed condition by the presence of one externalmagnet and the presence of a second magnet will cause one or the otherof the sections to assume an open circuit condition What is claimed is:

1. Apparatus comprising two terminals and between said terminalsmagnetically responsive switching means responsive to the presence of afirst magnet to maintain an open or a closed circuit condition betweensaid terminals and responsive to the presence of said first magnet and asecond magnet to change the circuit condition between said terminals;said switching means including first and second contact means which arerespectively normally open and normally closed, one of said contactmeans being responsive to a first magnetic force, which force isinefiective to change the open or closed condition of the other contactmeans, to assume the same open or closed condition as said other contactmeans, the introduction of a second magnetic force being efiective tochange the open or closed condition of one of the said contact means;each of said contact means including relatively displaceable contacts atleast one of which is of non ma netic material, sard first and secondcontact means each mc udmg magnetically responsible spring means fordisplacing at least one of the associated contacts and normallypositioned for keeping the contacts of the first contact means open andthe contacts of the second contact means closed, the spring means of thefirst contact means responding to a first magnetic force to enable theassociated contacts to be closed, the presence of a second magneticforce being effective on at least one of the spring means to open thecontacts of the associated contact means.

2. Apparatus as claimed in claim 1 comprising means to adjust theresponsiveness of at least one of the spring means to magnetic forces.

3. Apparatus as claimed in claim 1 comprising an envelope encapsulatingsaid contact means.

4. Apparatus as claimed in claim 1, wherein one of the contacts of eachof the respective contact means is connected in a fixed electricallyconductive continuous structure, and the spring means are electricallyconductive and respectively maintain the contacts thereon yieldinglyagainst and spaced from said fixed structure.

5. Apparatus as claimed in claim 1, wherein the spring means includeelectrically conductive spring elements and magnetic members thereon.

6. Apparatus as claimed in claim 1, wherein one of the contacts of oneof the contact means is a ring encircling the other contact thereto, thelatter said contact being supported by said spring means within saidring for radial displacement against the same.

7. Apparatus as claimed in claim 2, wherein one of the contact meansincludes support means yieldably supporting the contacts thereof inengaged relation, said magnetically responsive spring means beingpositioned to engage and displace at least one of said support means.

8. Apparatus as claimed in claim 1, wherein the spring means are ofdifferent strengths.

9. Switching apparatus comprising an electrically conductive ring, acontact within said ring, and magnetically responsive spring meanssupporting said contact for displacement against said ring.

10. Apparatus as claimed in claim 9, wherein said spring means includesa spring coaxially aligned with said ring and a magnetic member on thespring.

11. Apparatus as claimed in claim 10 comprising means to adjust theeffective strength of said spring.

12. Apparatus as claimed in claim 10 comprising means encapsulating thering, the contact and spring means and including terminal membersconnected to said ring and spring means.

13. Switching apparatus comprising contacts, supports supporting thecontacts in normally engaged relation but enabling the displacement ofat least one of the contacts to separate the same, and magneticallyresponsive means for engaging at least one of the supports andresponding to magnetic forces to separate said contacts.

14. Apparatus as claimed in claim 13, wherein the magneticallyresponsive means includes a spring and a magnetic member on said spring.

15. Apparatus as claimed in claim 14 comprising a sphere on said spring,said supports including spherical sections cooperatively encircling saidsphere.

16. Apparatus as claimed in claim 14 comprqsing means to adjust thestrength of said spring.

1. Apparatus comprising two terminals and between said terminalsmagnetically responsive switching means responsive to the presence of afirst magnet to maintain an open or a closed circuit condition betweensaid terminals and responsive to the presence of said first magnet and asecond magnet to change the circuit condition between said terminals;said switching means including first and second contact means which arerespectively normally open and normally closed, one of said contactmeans being responsive to a first magnetic force, which force isineffective to change the open or closed condition of the other contactmeans, to assume the same open or closed condition as said other contactmeans, the introduction of a second magnetic force being effective tochange the open or closed condition of one of the said contact means;each of said contact means including relatively displaceable contacts atleast one of which is of nonmagnetic material, said first and secondcontact means each including magnetically responsible spring means fordisplacing at least one of the associated contacts and normallypositioned for keeping the contacts of the first contact means open andthe contacts of the second contact means closed, the spring means of thefirst contact means responding to a first magnetic force to enable theassociated contacts to be closed, the presence of a second magneticforce being effective on at least one of the spring means to open thecontacts of the associated contact means.
 2. Apparatus as claimed inclaim 1 comprising means to adjust the responsiveness of at least one ofthe spring means to magnetic forces.
 3. Apparatus as claimed in claim 1comprising an envelope encapsulating said contact means.
 4. Apparatus asclaimed in claim 1, wherein one of the contacts of each of therespective contact means is connected in a fixed electrically conductivecontinuous structure, and the spring means are electrically conductiveand respectively maintain the contacts thereon yieldingly against andspaced from said fixed structure.
 5. Apparatus as claimed in claim 1,wherein the spring means include electrically conductive spring elementsand magnetic members thereon.
 6. Apparatus as claimed in claim 1,wherein one of the contacts of one of the contact means is a ringencircling the other contact thereto, the latter said contact beingsupported by said spring means within said ring for radial displacementagainst the same.
 7. Apparatus as claimed in claim 2, wherein one of thecontact means includes support means yieldably supporting the contactsthereof in engaged relation, said magnetically responsive spring meansbeing positioned to engage and displace at least one of said supportmeans.
 8. Apparatus as claimed in claim 1, wherein the spring means areof different strengths.
 9. Switching apparatus comprising anelectrically conductive ring, a contact within said ring, andmagnetically responsive spring means supporting said contact fordisplacement against said ring.
 10. Apparatus as claimed in claim 9,wherein said spring means includes a spring coaxially aligned with saidring and a magnetic member on the spring.
 11. Apparatus as claimed inclaim 10 comprising means to adjust the effective strength of saidspring.
 12. Apparatus as claimed in claim 10 comprising meansencapsulating the ring, the contact and spring means and includingterminal members connected to said ring and spring means.
 13. Switchingapparatus comprising contacts, supports supporting the contacts innormally engaged relation but enabling the displacement of at least oneof the contacts to separate the same, and magnetically responsive meaNsfor engaging at least one of the supports and responding to magneticforces to separate said contacts.
 14. Apparatus as claimed in claim 13,wherein the magnetically responsive means includes a spring and amagnetic member on said spring.
 15. Apparatus as claimed in claim 14comprising a sphere on said spring, said supports including sphericalsections cooperatively encircling said sphere.
 16. Apparatus as claimedin claim 14 comprqsing means to adjust the strength of said spring.